{'CH4' : 'opls_138', 'HC' : 'opls_140'; 'CCH3' : 'opls_135', 'CC2H2' : 'opls_136', 'CC3H' : 'opls_137', 'CC4' : 'opls_139',#alkane
'CCH2O' : 'opls_157','OCH' : 'opls_154','HO' : 'opls_155','CC2HO' : 'opls_158','CC3O' : 'opls_159',#alcohol
'OC2' : 'opls_180','CH3O' : 'opls_181','CH2O' : 'opls_182','HC' : 'opls_185'#ether}